1. Field of the Invention
The present invention relates to a method of manufacturing multilayer printed wiring board.
2. Description of the Related Art
In a conventional printed wiring board, high densifying of printed wiring circuits and downsizing of the printed wiring board itself are promoted. To this end double sided and to multilayer printed wiring boards have been developed and put into practice.
Manufacture of multilayer printed wiring board comprises an inner layer forming process, a laminating process, a through hole process, an outer layer forming process and a later manufacturing process as shown in FIG. 7.
In the method of manufacturing multilayer printed wiring boards, as a means for connecting respective layers, through hole connections are used, as shown in FIG. 7. Through hole plating is accomplished by copper electroless deposition or plating and copper electroplating.
In the connecting method using through hole plating, however, the plating apparatus is large, the cost of equipment is high and at the same time, the working environment is difficult. Also a severe requirement is imposed on the control of plating solution itself, resulting in a number of problems, such environmental problems resulting from the use of the plating solution.